Photogrammetry and Multi-Headed Theodolite Systems as Complementary Tools

1993 ◽  
Vol 9 (03) ◽  
pp. 167-172
Author(s):  
Eric L. Boyer ◽  
Peter L. Sparacino
Keyword(s):  
High Risk ◽  
Controlled Environment ◽  
Complex Structures ◽  
Structural Members ◽  
Ship Structure ◽  
Large Complex ◽  
Methods And Techniques ◽  
Traditional Process ◽  
Risk Venture

Foundations for wet accumulator bottles (WABs) are large, complex structures that require fabrication in accordance with exacting dimensional tolerances. WABs are those tanks that store steam for the launching of aircraft off aircraft carriers. The traditional process for fabrication and installation of WAB foundations is a high-risk venture not only from cost and scheduling perspectives, but also from a geometrical perspective. The WAB foundations consist of two units, each with four structural members and two padeyes that require fabrication and installation with respect to an imaginary WAB centerline. Through the complementary use of photogrammetry and a multi-headed electronic theodolite system, the foundations can be fabricated in the shop to the correct shipboard geometry, and installed within tolerances and within cost and schedule. With all of the fabrication completed in the controlled environment of the shop, all structural, fabrication, and installation problems can be alleviated before the actual shipboard installation. This paper explains the methods and techniques for using photogrammetry and a multi-headed electronic theodolite system as complementary tools. It explains the practicality of collecting dimensional data from the existing ship structure using photogrammetry, and using a multi-headed electronic theodolite system to assist in the fabrication of the WAB foundations.

Selection of Degrees of Freedom for Dynamic Analysis

1987 ◽  
Vol 109 (1) ◽  
pp. 65-69 ◽  
Author(s):  
K. W. Matta
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
General Purpose ◽  
Component Mode Synthesis ◽  
Complex Structures ◽  
Large Complex ◽  
Static Condensation ◽  
Basis Vectors ◽  
Selection Of

A technique for the selection of dynamic degrees of freedom (DDOF) of large, complex structures for dynamic analysis is described and the formulation of Ritz basis vectors for static condensation and component mode synthesis is presented. Generally, the selection of DDOF is left to the judgment of engineers. For large, complex structures, however, a danger of poor or improper selection of DDOF exists. An improper selection may result in singularity of the eigenvalue problem, or in missing some of the lower frequencies. This technique can be used to select the DDOF to reduce the size of large eigenproblems and to select the DDOF to eliminate the singularities of the assembled eigenproblem of component mode synthesis. The execution of this technique is discussed in this paper. Examples are given for using this technique in conjunction with a general purpose finite element computer program GENSAM[1].

Stress Distribution in Joints in Panel Structures

2015 ◽  
Vol 1124 ◽  
pp. 209-218
Author(s):  
Pavel Svoboda ◽  
Karl Heinz Winter
Keyword(s):  
Practical Experience ◽  
Elastic Behavior ◽  
Complex Structures ◽  
Structural Elements ◽  
Structural Members ◽  
Long Term Effects ◽  
Linear Elastic ◽  
The Past ◽  
Current Design

Reinforced and pre-stressed concrete have been used increasingly for various kinds of complex structures in the past decades. The structures assembled from panels belong into this group. The current design methods rely on linear elastic analyses based on empirically derived material laws assuming homogeneous and isotropic material. Practical experience and various investigations however have indicated that majority of structures and structural elements are in fact stressed beyond the range of linear elastic behavior. In addition, long term effects may have a significant influence on the structural behavior of this category of structures and structural members.

A Statistical Analysis of Corrosion Wastage of Transverse Members in Single Hull Tankers

2006 ◽  
Author(s):  
Swieng Thuanboon ◽  
David S. Tordonato ◽  
William Navidi ◽  
David L. Olson ◽  
Brajendra Mishra ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Weibull Function ◽  
Structural Members ◽  
Ship Structure ◽  
Corrosion Rates ◽  
Protection Systems ◽  
Oil Tankers ◽  
The Relationship ◽  
Derivatives Of ◽  
Best Fit

Corrosion wastage of structural members in oil tankers over the time causes variability in structural properties. Corrosion is a function of many variables and uncertainties, such as the types of corrosion protection systems used, types of cargo, temperature, humidity, etc. The traditional engineering and analysis, which uses simplified deterministic approaches to account for this time-dependent reliability or risk of aging ship structure, is not suitable. This investigation explores the use of statistical analysis approaches to predict corrosion wastage in oil carrying tankers. Corrosion wastage measurements from transverse members of 115 oil tankers were collected to add to an extensive corrosion wastage database. Lognormal function was found to best fit the collected data when compared to other methods, such as the Weibull function. Linear regression in the form of three mathematical models of corrosion wastage, developed by considering age of ship, coating life, and the location of the transverse members, is used to indicate the relationship between corrosion wastage and age of ship. Corrosion rates were determined by the derivatives of the corrosion wastage. The results show that corrosion wastage may accelerate after twenty years of service. It is expected that the study will help identify which structural members may be more susceptible to corrosion wastage and require more frequent inspection.

Multi-damage localization on large complex structures through an extended delay-and-sum based method

2016 ◽  
Vol 15 (1) ◽  
pp. 50-64 ◽  
Author(s):  
Shengbo Shan ◽  
Jinhao Qiu ◽  
Chao Zhang ◽  
Hongli Ji ◽  
Li Cheng
Keyword(s):  
Damage Localization ◽  
Complex Structures ◽  
Large Complex

Trends in sweet cherry production.

2021 ◽  
pp. 1-8
Author(s):  
Lynn E. Long ◽  
Gregory A. Lang ◽  
Clive Kaiser
Keyword(s):  
High Risk ◽  
Crop Yield ◽  
Sweet Cherry ◽  
Organic Production ◽  
Market Potential ◽  
Future Market ◽  
Perceived Risks ◽  
Global Trend ◽  
Reduce Risk ◽  
Risk Venture

Abstract This chapter focuses on the global trend of sweet cherry production. It covers the economics, crop yield, crop quality and organic production. As sweet cherry production continues to expand worldwide, each producer must decide whether to increase production (either through the renovation of old orchards or expansion into new sites), continue at a steady pace or decrease acreage and thus reduce risk but also yields. Since growing cherries is a high risk venture, the best way to proceed will depend on past successes and failures, perceived risks, the possibilities for mitigating those risks and future market potential.

Evaluation of the Heat Dissipated inside Compartments by Internal Structural Members on High Speed Aircraft

1966 ◽  
Vol 70 (664) ◽  
pp. 534-537
Author(s):  
R. Le Claire
Keyword(s):  
Internal Structure ◽  
High Speed ◽  
Complex Structures ◽  
Structural Members ◽  
Analogy Method ◽  
Electrical Analogy

This note deals with an extension of the basic fin theory, as found in refs. 1 and 2, suitably modified to estimate the heat dissipated by internal structure such as consoles, floors, bulkheads, and so on. It also outlines the electrical analogy method applied to complex structures.

Sign in / Sign up

Export Citation Format

Share Document